If you look under the hood of any race car, nine times out of ten, you’ll see a vacuum pump connected to the engine. A vacuum pump is a device that is added to any engine to help control “blow by”. As engine RPM increases, the pressure created in the crankcase will cause the piston rings to start moving upward as the pressure builds. This inhibits ring seal to the cylinder walls, which causes more blow-by. The increased pressure developed in the pan then forces oil past the rings. A vacuum pump can resolve this problem by reducing, eliminating, or even creating negative pressure in the engine. This results in better piston ring seal, less oil contamination and oil leaks, longer engine life, and more horsepower.
Usually, a vacuum pump will have hoses connected to it that come from either one or both valve covers. It is designed to pull air from the engine, thus reducing the pressure that inherently builds in the crankcase due to combustion gases reaching the oil pan. Vacuum pumps vary in the amount of vacuum they can pull, so the potential vacuum that a pump can create is limited by cfm. Because of this limitation, if the pump is not properly sized, plumbed, and geared correctly, it may not be up to the task of moving enough air to create a vacuum in the crankcase.
If you are not sure if a vacuum pump is a required performance part on your car, you might want to check out this video from Jegs. In the video, Kenny Wallace explains the different options available from Moroso that fit your small to big block engine. By choosing either a three or four-vane pump system, you can increase the horsepower and efficiency of your engine.
If you want to read all about vacuum pumps and crankcase evacuation systems, check out this article on dragzine.com